In principle, a combo box is a combination of a list box and an edit box (Figure 7.31). The combo box is used for selecting an item from a list, in the same way as for a list box, but in this case the item may be typed in by the user in the attached edit box.

The combo box consists of a list box with an edit box immediately above it. To the right of the edit box is a button with a down-pointing arrow. Items are selected from a combo box in one of two ways: either (1) click on the down-pointing to display the list (if not already shown) and then click on an item, or (2) type an entry directly into the edit box (either an existing item or a new item). The way in which the combo box can be used is determined by the style of the box, which is set when the box is created: